I find Google’s patent search to be a good resource for inspiration and research.
While searching for things dulcimer I came across this very interesting patent.
Aside from the foot pedal mechanism what interests me most about this design is the dulcimer itself. The wide hourglass shape, the modified scroll and the use of f-holes are features I have considered to be relatively recent developments in the design of dulcimers. This patent was filed in 1933!
On another note, European dulcimer player John Molineaux made a dulcimer with pedals for fretting extra bass strings similar to this design in the 1970’s.